6 Protein Myths That Are Messing With Your Diet

It's a fact that your body can't properly repair or generate muscle without the full suite of essential amino acids found in food sources of protein. But just eating protein isn't enough to build or maintain strength and muscle mass, Baum says. "You need exercise to do that," she explains.  (Here's what a perfect day of eating enough protein looks like.)

Especially as you age, when muscle loss, or "wasting," increases your risk of mobility issues and serious falls, both aerobic and resistance exercise are necessary to help your body hold on to and build muscle, says Wayne Campbell, PhD, a professor of nutrition science at Purdue University.

Pretty much everything you put in your mouth (apart from water and soda) contains at least a little protein. But not all food sources of protein contain the essential amino acids your body requires to support muscle and cell health, Baum says.

"There's a huge difference between animal and plant sources of protein," she explains. "While animal foods"—meat, dairy, eggs, fish—"are complete sources of essential amino acids, plants are not." (Is animal protein causing your inflammation?)

Also, not all the protein packed into plants is bioavailable, she says. "The fiber in some plant sources of protein may prevent the digestion and absorption of some amino acids," she explains. 

That said, you don't need animals in your diet to get the protein amino acids your body needs. But if you're eating a diet largely free of animal products, you need to put a little more thought into your menus, Baum says. (Try these 3 plant proteins.)

Try to combine legumes like beans, lentils, and peanuts with whole grains. Together, legumes and whole grains provide all the essential amino acids you require, says Winston Craig, PhD, professor emeritus of nutrition at Michigan's Andrews University.

The average American eats roughly 80 to 90 grams of protein a day—roughly twice the daily amount recommended by the National Academy of Medicine, says Douglas Paddon-Jones, PhD, a professor of nutrition and metabolism at the University of Texas Medical Branch.

"If you're eating an omnivorous diet"—that is, a diet that includes both plants and animals—"protein inadequacy is really not an issue," Paddon-Jones says. (Here are 4 types of people who should be on a high-protein diet.)

Also, in terms of both building muscle and satisfying hunger, "there's a limit to how much protein your body can actually use," he explains. For most people, that limit is somewhere between 25 and 30 grams per meal, he says. That's roughly the amount in two eggs or a three-ounce portion of meat, according to USDA nutrition estimates. 

Instead of trying to pack more protein into your diet, Paddon-Jones says most of us should look to redistribute the protein we're already getting. He points out that many of us eat little to no protein at breakfast and a heaping helping at dinner.

Rather than a big slab of beef with beans, rice, and other plant sources of protein in the evening, he recommends reducing your protein portions at night and adding some of that meat or veggie protein to your breakfast. 

Baum says she sees this misconception most among young men. These guys feel like they need to slam a supersized protein shake after every gym visit in order to maximize their workout gains.

"People in Arnold Schwarzenegger–type bodybuilding competitions probably need protein every 4 hours," she says. But for the rest of us, eating protein with our meals will provide our muscles with everything they need to take advantage of exercise, she says.

Research backs her up. A recent study on "protein timing" in the Journal of the International Society of Sports Nutrition found that downing the stuff right after a workout had no beneficial effects on muscle growth or strength, compared with eating the same amount of protein later with meals.

Feeling wiped out all the time could be a sign that your body's running low on protein. But this is only going to occur if your protein stores are very depleted—we're talking severe protein shortages, not cutting out protein for a meal or two, Campbell says.

If you're vegan (or otherwise avoiding animal sources of protein) AND you're wiped out all day AND your limbs seem to be getting skinnier even though your gut and waist size aren't changing, then it's possible you may not be consuming enough protein, Campbell says. (Talk with a dietitian.)

But in most cases, feeling tired probably has nothing to do with your protein intake, he says.

Baum says protein can increase "satiety"—or feelings of sustained fullness following a meal. But there's a limit to this effect. "You can still overdo it and eat too much protein, and it can still make you fat," she says.

If you're looking to add protein foods to your diet in order to knock down hunger and support muscle health, she recommends swapping carb calories for protein calories—as opposed to simply adding protein to whatever you're currently eating.

One example: If you usually eat a whole wheat bagel with cream cheese for breakfast, don't just add eggs or Greek yogurt to your plate. Instead, reduce your bagel portion to make room for those eggs or yogurt.